Process cheese is produced by crushing cheese ingredients such as natural cheese, heating and melting, and then emulsifying (this is defined in the above-mentioned ministerial ordinance). In a continuous production method for process cheese type, these processes are continuously performed.
For example, Published Japanese Translation No. H9-502886 of the PCT International Publication suggests a continuous production method for process cheese in which a process a) for preparing substantial homogeneous cooked liquid materials flow from cheese ingredients needed to obtain cheese products, a process b) for heat treating the cooked liquid materials flow, if necessary, a process c) for cooling the cooked liquid materials flow to a temperature suitable for an adjustment of the viscosity thereof, if necessary, a process d) for circulating all or a part of the cooked liquid materials flow in a closed circulation system at least at the beginning of this process and shear stress is applied to the cooked liquid material flow to adjust the viscosity thereof to a desirable value, and a process e) for taking out the cooked liquid materials flow from the closed circulation system and after any other desired treatments and/or a temporary storage, the cooked liquid materials are taken out as a final product.
In addition, for example, Japanese Unexamined Patent Application, First Publication No. H11-221016 suggests process cheese having suitable flow property which is heated in an electric oven, and contains moisture in a range from 43 to 55% by weight and fat in a range from 59 to 75% by weight in a solid content, and which has a viscosity in a range from 500 to 1,500 cP at 70° C. (measured by an oscillating viscometer).
The oscillating viscometer, for example, is disclosed in Japanese Examined Patent Applications, First Publications Nos. H5-20692, H6-25729, and H8-30674, and Japanese Patent (Granted) Publications Nos. 2622361 and 3348162.
In production processes for process cheese type, properties of melted cheese vary depending on several factors such as kinds, maturation degree, composition, melting condition strongly influences processes after melting of cheese and quality of products, it is important to adjust melting conditions and thereby to stabilize the viscosity of the melted cheese. However, online measurement of the viscosity of melted cheese is difficult, and in the past, the viscosity of melted cheese is visual evaluated by an operator or measured by an offline viscometer for convenience. However, the viscosity of melted cheese is not measured visually. In addition, when a part of melted cheese is picked up from a production line and the viscosity of the cheese is measured by an offline viscometer, since time is needed for the measurement, a problem of a time lag, in which melted cheese is transferred to a next process during measurement, arises. Therefore, it is difficult to suitably adjust and control automatically the production conditions based on offline measurement data.
Many online viscometers have been used and measurement of agitation torque, pressure drop during transfer of melted cheese, and the like have been measuring to evaluate the viscosity of melted cheese. For example, Published Japanese Translation No. H9-502886 of the PCT International Publication estimates the viscosity based on pressure drop measured by a built-in online measuring device. In Japanese Unexamined Patent Application, First Publication No. H11-221016, the end of a probe of an oscillating viscometer is contacted with process cheese and thereby the viscosity thereof is measured.
However, among conventional viscosity measuring methods, a method, in which the viscosity of process cheese is estimated based on pressure drop during transfer of melted cheese or agitation torque, does not readily measure an exact viscosity. When process cheese type is produced by controlling production conditions based on such inexact viscosity, there is a possibility that process cheese having desired quality is not produced (For example, please refer a following Comparative Example).
In addition, when an attempt is made to measure the viscosity of melted cheese using an online oscillating viscometer having a transducer (probe), since cheese adheres to the transducer (probe) and measurement of the viscosity is impossible, it is very difficult to online measure the viscosity of melted cheese.
In consideration of the above-described problems, an object of the present invention is to provide a continuous emulsification process for heating and emulsifying process cheese type continuously in which the accurate viscosity measured inline is obtained and production conditions are controlled automatically and equipment therefore, and a continuous production method for process cheese type and equipment therefor.